WASHINGTON — "Hillary: The Movie" had little effect on last year's election campaign, but it could have a profound impact on a century of election laws that restrict corporations from promoting or attacking candidates for public office.

The Supreme Court took up a case Tuesday involving the 90-minute documentary that attacked now-Secretary of State Hillary Clinton when she was running for president.

Since 1907, federal law has barred corporations from directly spending for or against candidates. The same limit was put on unions in 1947.

Those restrictions have come under attack by those who maintain they violate 1st Amendment guarantees of free speech.

The Supreme Court now has a five-member majority that takes the free-speech view. And during oral arguments Tuesday, the only question seemed to be whether the justices would strike down some of the legal restrictions on corporate-funded campaign ads or all of them.

Citizens United, a small conservative group based in Washington, made "Hillary: The Movie," in which a parade of critics, including Newt Gingrich and Ann Coulter, derided Clinton as dishonest and dishonorable.

The group used corporate money, in part, to pay for its film. So when it sought to advertise the movie, the group ran into the federal campaign restrictions.

Citizens United sued to challenge those restrictions. Former U.S. Solicitor General Theodore Olson, the group's attorney, urged the court to declare that corporations have the same free-speech right as others. "Freedom is being smothered," he said of the regulations.

In the past, Justices Anthony Kennedy, Antonin Scalia and Clarence Thomas have said limits on corporate-funded ads should be struck down as a "censorship scheme." That meant Olson needed only the support of President George W. Bush's two appointees for a majority.

One of them, Justice Samuel Alito said that if the government has the power to ban broadcast ads, it also could ban books.

"That's pretty incredible," Alito said.

Deputy Solicitor General Malcolm Stewart, who defended the law, said the restrictions could not ban the publication of a book but could limit a company's use of money to put one out.

The book-ban metaphor hung over the argument. Justice Kennedy noted books now can be read on Amazon's Kindle, an electronic device. If the Constitution in theory allows the government to forbid corporate-funded campaign books, he said, it also could restrict books that may be received from a wireless transmission.

Chief Justice John Roberts expressed surprise at that. "If it has one name, one use of a candidate's name, it could be covered?" Roberts asked.

"That's correct," Stewart replied.

"It's a 500-page book, and at the end it says, so vote for X. The government could ban that?" Roberts asked.

Yes, Stewart said again. The Constitution would allow a law that forbids the use of corporate funds to pay for such a campaign book, he said.

The exchange left little doubt that a majority of the justices would side with Citizens United. How far the ruling is likely to reach probably depends on the chief justice.

Roberts could press for a narrow ruling that would say that a 90-minute documentary on a DVD deserves more free-speech protection than a 30-second attack ad. Or he could say that a small, non-profit corporation deserves to be exempted from some rules, including disclosing its donors.

But the tenor of the argument suggested the court's conservative bloc will seek broader free-speech protections for corporate-funded political ads.